Sinus Tachycardia is defined by rate.

Sinus Tachycardia is defined by rate.

• A. 60-100
• B. <60
• C. ">100"
• D. Rate varies

Answer: (C)

Sinus tachycardia is defined by a heart rate that exceeds the normal resting range. In adults, a typical resting heart rate is about 60 to 100 beats per minute, so when the rate climbs above 100 bpm, it is categorized as tachycardia. The “sinus” part means the rhythm still originates from the sinoatrial node with normal P waves and a regular rhythm, but the key diagnostic criterion here is the rate itself. A rate under 60 bpm is bradycardia, not tachycardia. If the rate varies, that does not define sinus tachycardia, because the criterion is a fixed threshold above 100 bpm. Therefore, the correct understanding is a rate greater than 100 beats per minute.

Sinus tachycardia is defined by a heart rate that exceeds the normal resting range. In adults, a typical resting heart rate is about 60 to 100 beats per minute, so when the rate climbs above 100 bpm, it is categorized as tachycardia. The “sinus” part means the rhythm still originates from the sinoatrial node with normal P waves and a regular rhythm, but the key diagnostic criterion here is the rate itself. A rate under 60 bpm is bradycardia, not tachycardia. If the rate varies, that does not define sinus tachycardia, because the criterion is a fixed threshold above 100 bpm. Therefore, the correct understanding is a rate greater than 100 beats per minute.